On 2002-06-25 14:53, "ext Jonathan Borden" <jonathan@openhealth.org> wrote:
> Patrick Stickler wrote:
>
>>
>> On 2002-06-24 20:58, "ext Jonathan Borden" <jonathan@openhealth.org>
> wrote:
>>
>>
>>> The past version of the RDF MT WD discussed 'asserted triples' with the
>>> implication that 'unasserted triples' might also exist. This language
> was
>>> removed in the current WD, so we must conclude that the current
> intention of
>>> the current RDF MT WD is that RDF reification in fact is not an
> acceptable
>>> means of representing an 'unasserted triple'. If I am incorrect, the RDF
> MT
>>> should state this relationship -- that is the purpose of a model theory,
>>> isn't it?
>>
>> I agree. The MT would need to be tweaked to provide a resonable
>> treatment of reification with regards to expressing unasserted
>> triples, so as to provide for layering.
>>
>
> Ok. So then, in this case, one _could_ say that RDF reification is _a_
> mechanism to represent the so-called "dark triples" (I prefer the term
> "unasserted"), and hence "dark triples" have actually been present in RDF
> all along.
Exactly. We don't (absolutely) need to add anything to RDF to provide
for unasserted triples.
> The only quibble I would have with that is the syntax, but as you have
> suggested, the syntax could be changed.
Well, the syntax wouldn't (technically) need to change, only the
parsing algorithm, so that it would give special meaning to
rdf:Statement when occurring with an rdf:about or rdf:ID in it.
So the syntax itself, per se, wouldn't change at all.
> I understand, now, that your use of the N3 rule was intended to be used by a
> "higher level" than RDF itself, e.g. by OWL, and agree. As long as RDF
> provides a facility for unasserted triples, such mechanisms, as you have
> exemplified, might exactly be used to "assert" as a fact, some triple that
> had not been asserted by base RDF. Note that this is not a problem, because
> the unasserted triple is not "negated" -- by being "unasserted" we are _not_
> saying that the triple is _not true_ -- simply we are not assigning a truth
> value at all -- at this level. Just as we do not assign truth values to the
> character sequence ('n','o','t') until it is 'transformed' via the rules of
> the english language to the symbol "not" which has meaning when used in
> sentences.
>
> Jonathan
Exactly.
Cheers,
Patrick
--
Patrick Stickler Phone: +358 50 483 9453
Senior Research Scientist Fax: +358 7180 35409
Nokia Research Center Email: patrick.stickler@nokia.com